Formulation and Evaluation of Gastroretentive In situ Gel of Captopril

The objective of the work was to formulate and evaluate gastroretentive in situ gel of captopril to reduce dosing frequency by prolonged gastric retention. Gastroretentive in situ gel of captopril was formulated by ion gelation method. A 32 full factorial design was applied to study the effect of different concentration gellan gum and HPMC K4M on % drug release at 6 h, viscosity and floating lag time. All batches were evaluated for various parameters like pH, gelling capacity, gelling time, floating lag time, floating time, viscosity, drug release and stability study. Optimized formulation shows in vitro drug release of 67.09±1.9 in 6 h and 100.46±1.1 in 12 h, viscosity 165±1.03 cp and floating lag time 24±0.9 sec. From all the evaluation parameter and experimental design, it was concluded that the drug release rate decreases with increase in concentration of gellan gum and HPMC K4M. Floating lag time and viscosity increases with increase in concentration of gellan gum and HPMC K4M.The in vitro drug release kinetic revealed that the Higuchi model is followed and drug release is by fickian diffusion.